Strength and rigidity of Quick Install pushrods are second only to heavy-duty one-piece pushrods Tube material starts out as 7/16ö rod OD, then gets turned down to 3/8ö OD leaving heavy duty 7/16ö - 20 threads for the base and jam nut 0.134ö wall thickness Jam nut slides up the pushrod Base then loosens up into the pushrod to allow Quick Install access Individual length exhaust and intake pushrods Install without the removal of rocker covers Correct pushrod/lifter adjustment requires starting with fully pumped up lifters. Quick Install pushrods have 7/16ö - 20 threads per inch. 0.050ö adjustment per turn. Two turns = 0.100ö.. PUSHRODS ADJ QUIK TC 99-